单元测评(三) Unit 3 Under the sea
(时间：90分钟 满分：110分)
第一部分 阅读理解(共两节；满分30分)
第一节 (共10小题；每小题2分，满分20分)
阅读下列短文，从每题所给的四个选项(A、B、C和D)中，选出最佳选项。
A
If you travel to a new exhibit at the San Francisco Greenhouse of Flowers, you will have a chance to see some meateating plants. Take bladderworts, a kind of such plant, for example. They appear so small and grow in a quiet pool. But these are the fastestknown killers of the plant kingdom, able to catch a small insect in 1/50 of a second using a trap (陷阱) door!
Once the trap door closes on the animal falling into it, the enzymes (酶) similar to those in the human stomach slowly digest the insect. When dinner is over, the plant opens the trap door and is ready for trap again.
Meateating plants grow mostly in wet areas with soil that doesn't offer much food value. In such conditions, these amazing plants have developed insect
